Polyethylene is a plastic material that is commonly applied to paper for use as a barrier type of coating. Paperboard coated with polyethylene has chemical, tear and puncture resistance, heat sealability, gas, moisture and grease resistance, and durability on folding. For these reasons, polyethylene coated paperboard is used extensively to manufacture various types of containers, such as milk cartons as well as a variety of other paper products.
The trim and scrap from manufacturing coated paperboard as well as the trim from the different products made from polyethylene coated paperboard is known in the art as "polyethylene broke". Polyethylene broke from the manufacture of milk cartons contains generally about 8% to 12% by weight of polyethylene. Normally, polyethylene broke is chopped, baled and fed into a hydropulper where the fiber content of the broke is discharged through screens as an aqueous slurry, and after cleanup, is reused in paperboard manufacture. The polyethylene content of the broke, together with some fiber that is present, is also discharged from the hydropulper as a slurry. Because of the fiber content, however, the polyethylene scrap is not particularly suited for recycling. Consequently, the separated polyethylene material usually is dewatered and then transported to a landfill where it is dumped.
Efforts to recover the polyethylene in an economic manner have not been successful. U.S. Pat. No. 3,226,343 discloses a chemical solvent process of recovering polyethylene from cellulosic fibers, but here special equipment and processing costs have rendered the process economically unsuitable. There is also the problem of special handling resulting from the use of solvents.